A computer system typically comprises a plurality of electronic components. Such components may include a central processing unit (CPU), a chipset, and a memory. During operation, the components dissipate heat. In addition, voltage stepping inside the computing system also generates heat. If the CPU, or any other electronic component, becomes overheated, performance may suffer and the component's life may be depreciated.
A thermal management system is typically used to remove heat from a computer system. An example of a thermal management system is a two-phase cooling loop. A two-phase cooling loop also uses a pump to circulate a working fluid to cool a component of a system. A two-phase loop typically uses a working fluid such as water. An evaporator or cold plate picks up heat from the component. FIG. 1 depicts a prior art cross-sectional view of an evaporator 120 that picks up heat from a component 110. The evaporator has uniformly spaced micro-channels that provide a path for the heat to travel from the component 110. The heat causes the working fluid to change phase from a liquid to a mixture of liquid and vapor or pure vapor. The working fluid is output from the evaporator to a heat exchanger, condenser, or heat sink. The heat exchanger is typically coupled to a fan that rejects the heat from the working fluid to the ambient air. The vapor condenses in the heat exchanger, converting the working fluid back to liquid. A pump is used to drive the working fluid to the evaporator to complete the loop.
Another example of a thermal management system is a refrigeration loop. Similar to a two-phase cooling loop, a refrigeration loop may comprise a liquid phase and a vapor phase. A refrigeration loop typically uses a working fluid such as Freon to cool a component of a system. An evaporator picks up heat from the component. The heat causes the working fluid to change phase from a liquid to a mixture of liquid and vapor or pure vapor. A pump, working as a compressor, then transports the working fluid to a heat exchanger. The compressor compresses or increases the pressure of the gas, which results in increase in temperature of the fluid. The heat exchanger is typically coupled to a fan that rejects the heat from the working fluid to the ambient air, turning the working fluid back into a liquid. The liquid, however, is still at a high pressure. An expansion valve reduces the pressure of the working fluid and returns the working fluid to the evaporator to complete the loop. The fundamental difference between the refrigeration loop and the two-phase loop is that the heat exchanger in the refrigeration loop typically has a higher temperature than the heat exchanger in the two-phase loop.